Nelson Hart awaits his verdict in Gander, N.L. in this March 28, 2007 photo. THE CANADIAN PRESS/Tara Brautigam

The Supreme Court of Canada has agreed to hear a Crown appeal in the case of a Newfoundland man sentenced to life in prison after his two daughters drowned.

The Crown is asking the justices to overturn an appeal court ruling that ordered a new trial for Nelson Hart.

He was found guilty in 2007 of first-degree murder in the deaths of three-year-old twins Karen and Krista on Aug. 4, 2002, at Gander Lake in central Newfoundland.

Last fall, the Newfoundland and Labrador Court of Appeal ruled 2-1 that a confession Hart gave during an elaborate undercover RCMP operation should not have been entered as evidence.

Two of the appeal court judges ruled Hart's confession inadmissible. But the third judge said "the tricks employed by the undercover police were not such as to shock the conscience of the community" and weren't proven to be excessive coercion or inducement.

The RCMP launched the sting in February 2005 after the investigation stalled.

At his trial, court heard that Hart initially told detectives Krista fell in the water at a recreation area called Little Harbour. He said he couldn't swim, so he left his other daughter Karen behind as he drove for help.

Hart's trial would later hear that he headed 11 kilometres to his home, passing a hospital and businesses, to get his wife who also couldn't swim.

Karen was dead and Krista was floating unconscious on the water when police arrived. She later died in a St. John's hospital.

Court heard that Hart changed his story two months later, telling police he couldn't remember how his daughters wound up in the lake because he'd had an epileptic seizure at the time. He said he didn't mention it earlier for fear of losing his driver's licence.

The Mr. Big sting cost about $413,000 over four months as officers posed as criminal gang members. They recruited Hart to travel with them across Canada where he met other fake mobsters and was taken to restaurants, casinos, racetracks and strip clubs. Hart, who has a Grade 5 education and was on social assistance before the sting began, sometimes moved what he thought was stolen property.

Hart's defence lawyer has challenged the confession, saying his client needed money and was intimidated by what he thought were gang leaders when he tells police officers posing as mobsters on June 9, 2005, that he drowned his daughters.

Hart appears on video, re-enacting for another undercover officer how he said he shoved the girls from the Gander Lake wharf into the water.